Walsh told the Holmes Report he is now working as a freelance consultant for high growth tech companies, including Grabyo, a real-time TV clip sharing startup.

Spark CEO Alan Soucy said the agency retains several of its London-based accounts, among those Moo, Vidyo and URTurn.

“In London we continue to effectively service our clients through a combination of employees and consultants,” Soucy said.

Candice Yusim, who joined Spark as its Los Angeles MD earlier this year, left the firm in June to become VP at IPG’s entertainment shop PMK BNC. The Los Angeles market will now be serviced through Spark’s San Francisco hub and a “solid base” of regional consultants, Soucy said.

“San Francisco and New York have been stronger markets for us than London and Los Angeles,” he said, adding that Spark has grown about 14 percent to 50 employees this year with more hires expected in both New York and San Francisco.

“We'll continue to monitor Spark's business opportunities and may revert back to physical office locations at those locations in the future,” Soucy added.

Breaking into the Los Angeles market has proved difficult for several Silicon Valley agencies, including Bite which eventually closed its Los Angeles offering in 2011.